Students preparing for the CBSE Class 12 Biology Half Yearly Examination 2025 can now boost their preparation with this comprehensive collection of carefully designed Multiple Choice Questions (MCQs). These questions cover the entire syllabus of CBSE Class 12 Biology and are created by subject experts to ensure full alignment with the latest CBSE guidelines, exam pattern, and syllabus structure.
This set of 50 important MCQs is designed to help students revise key concepts, test their understanding, and build confidence ahead of their half-yearly exams. Below is the full list of MCQs along with the correct answers.
CBSE Class 12 Biology Half Yearly Important MCQs
- Gamete mother cells in humans are
A) Diploid and undergo mitotic divisions
B) Diploid and undergo meiotic divisions ✔
C) Haploid and undergo meiotic divisions
D) Haploid and do not divide - Assertion (A): Amoeba produce multiple minute amoebae through sporulation.
Reason (R): Sporulation involves meiotic division.
Correct option: C) A is true, but R is false ✔ - Ploidy of endosperm formed through apomixis:
A) 2n
B) 3n
C) 4n
D) 6n ✔ - In a false fruit like apple:
A) Ovary is infertile
B) Ovary does not undergo fertilization
C) Thalamus undergoes fertilization
D) Thalamus forms part of the fruit ✔ - Haploid cell in male human reproductive system:
A) Spermatid ✔
B) Sertoli cell
C) Leydig cell
D) Spermatogonium - Globozoospermia prevents sperm from:
A) Entering cervix
B) Penetrating ovum ✔
C) Leaving ejaculatory duct
D) Swimming to fallopian tube - Hormone present in both pregnant and non-pregnant female:
A) Relaxin
B) Prolactin
C) Progesterone ✔
D) HCG - Placenta shedding happens between:
A) (i) & (ii)
B) (ii) & (iii)
C) (iii) & (iv) ✔
D) (iv) & (v) - Apomictic seed formation ploidy of gametes:
A) True, but R is false ✔ - Miller-Urey experiment alignment condition:
A) Reactants ≥ products
B) Reactants < products ✔
C) Reactants = products
D) Reactants > products - Organisms in early Earth’s atmosphere were:
A) Aerobic & chemo-autotrophic
B) Anaerobic & chemo-heterotrophic ✔
C) Aerobic & chemo-heterotrophic
D) Anaerobic & chemo-autotrophic - Speciation major contributors:
A) Q & S only
B) R & T only
C) P, Q & S only ✔
D) Q, R & T only - NOT an assumption of Hardy-Weinberg principle:
A) Random mating
B) Emigration of species ✔
C) Large population size
D) No mutations - ELISA detects:
A) HIV DNA
B) HIV RNA
C) HIV antibody or antigen ✔
D) HIV reverse transcriptase - Immunity from COVID-19 vaccine:
A) Naturally acquired active
B) Naturally acquired passive
C) Artificially acquired active ✔
D) Artificially acquired passive - In complete DiGeorge Syndrome, impaired process:
A) Red blood cells
B) Thyroxine
C) Antibody production ✔
D) Antigen production - Fungal disease causing scaly skin lesions:
A) Ringworm ✔
B) Filariasis
C) Amoebiasis
D) Ascariasis - Infection NOT caused by worm:
A) Filariasis
B) Ringworm ✔
C) Roundworm
D) Elephantiasis - Assertion (A): Single-cell proteins can eliminate hunger.
Reason (R): Agricultural yield > microbial yield.
Correct option: C) A is true, R is false ✔ - Industrial product negatively affected by yeast:
A) Beer
B) Wine
C) Fruit juice ✔
D) Wheat bread - Microbe for immune modulation in pharma:
A) Aspergillus niger
B) Staphylococcus aureus
C) Trichoderma polysporum ✔
D) Saccharomyces cerevisiae - Constant in scaling up bioreactor process:
A) Only P, R, S
B) Only P, Q, R
C) Only Q, T, R
D) Only P, S, T ✔ - Suitable candidates for statin drug testing:
A) Swimmer
B) Dengue recovered
C) Gym trainer
D) High saturated fat consumer ✔ - Transgenic mice replacing monkeys because:
A) Only P
B) Only Q
C) Both P & Q ✔
D) Neither - Why perform gel electrophoresis after PCR?
A) Separate positive/negative DNA
B) Separate cloned MAP2 DNA ✔
C) Separate recombinant protein
D) Separate DNA from protein - Assertion (A): Energy used for growth is not transferred.
Reason (R): Growth increases biomass.
Correct option: D) A is false, R is true ✔ - Energy received by humans from producers:
A) 10%
B) 10% or 1%
C) 10%, 1% or 0.1% ✔
D) Humans not part of food web - Energy to snakes if producers generate 20,810 kcal:
A) 383 kcal ✔
B) 2081 kcal
C) 10,000 kcal
D) Cannot say - Carbon sink decline caused by:
A) Deforestation ✔
B) Population growth
C) Burning fossil fuels
D) Industrial activity increase - Examples of biodiversity:
A) Only (i)
B) Only (ii)
C) Only (ii) & (iii)
D) All (i), (ii), (iii) ✔ - BOD with removal of effluents:
A) Increases
B) Decreases ✔
C) Same
D) Increases then stagnates - Correct eutrophication process description:
A) Only P & R
B) P, R & S ✔
C) Q, R & T
D) All P, Q, R, S, T - Nutritive material outside embryo sac:
A) Protoplasm
B) Pericarp
C) Ectoderm
D) Perisperm ✔ - Male parts of flower collectively known as:
A) Androecium ✔
B) Filament
C) Anther
D) Gynoecium - Gamete mother cells in humans:
A) Diploid, mitotic
B) Diploid, meiotic ✔
C) Haploid, meiotic
D) Haploid, no division - Best survival population in stable habitat:
A) Only Q
B) Only R
C) Only P & R ✔
D) P, Q & R - True about reproduction:
A) Only P
B) Only Q ✔
C) Only P & Q
D) None - PCR mimics:
A) Ligation
B) Translation
C) Replication ✔
D) Transformation - Steam in bioprocessor:
A) Grow organisms
B) Add water
C) Maintain sterility ✔
D) Not required - Colonies by variant P:
A) Blue only
B) White only
C) Mixed
D) No colonies ✔ - Recombinant DNA made naturally in:
A) Prophase (mitosis)
B) Prophase I (meiosis) ✔
C) Prophase II (meiosis)
D) Not natural - Immuno-suppressants function:
A) Trigger allergy
B) Remove unhealthy tissue
C) Control cell-mediated response ✔
D) Differentiate self/non-self - Trees with broad leaves in which biome?
A) Arctic
B) Desert
C) Coastal
D) Rainforest ✔ - African midge larvae response to stress:
A) Regulation
B) Migration
C) Suspension ✔
D) Conformation - Genetic variation occurs in:
A) Only P
B) Only Q
C) P & Q
D) P & R ✔ - Brown-white fur cross result indicates:
A) Both heterozygous
B) Male homozygous
C) Male heterozygous ✔
D) Female heterozygous - % of eggs with round & green alleles:
A) 9%
B) 93%
C) 64%
D) 25% ✔ - Kernel color inheritance in wheat:
A) Only co-dominance
B) Only polygenic inheritance ✔
C) Both co-dominance & polygenic
D) Incomplete & polygenic - Indicator of unhealthy society:
A) ↑ Infant mortality ✔
B) ↓ Maternal mortality
C) Awareness of contraception
D) STD cure detection - Amniocentesis important despite ban:
A) Decline in sex ratio
B) Prevent STDs
C) Biological sex determination
D) Genetic disorder detection ✔
